The invention relates to a process for treating used metal and/or metal scrap and waste containing halogenated hydrocarbons simultaneously and at elevated temperatures, in which process part of the metal and/or metal scrap is converted into metal halogenides that are volatile under the conditions applied.
The disposal or processing of waste material containing halogenated hydrocarbons, particularly chlorinated and, to a lesser extent, the fluorinated hydrocarbons presents serious environmental problems. Specifically, polyvinyl chloride is contained in refuse in substantial amounts. These products cannot be incinerated as such, inasmuch as volatile, possibly toxic, compounds will then be formed. A possible solution was thought to be incineration of this type of refuse on board special incinerating ships in the open sea, and the resulting volatile halogen compounds would ultimately be dissolved largely in the sea water. But this is undesirable for environmental reasons, and the costs are rather high. It is also possible to remove the halogen compounds from the vent gases of the incinerator by means of special and expensive methods, but disposal of the removed halogen compounds itself presents difficulties. Furthermore, in view of the increasing shortage of raw materials, such a process is less attractive. It is more desirable to process this refuse into useful products.
Problems also arise in processing used metal, such as motorcar scrap, tin cans, cables, and the like, whether or not in the presence of halogenated hydrocarbons. These problems arise because the conventional processing methods generally result in a strong reduction in value of the material due to a loss in quality of the metal during processing. For instance, in the case of copper cables coated with polyvinyl chloride, the quality of the copper strongly falls when the cables are put in an incinerator. Moreover, many copper cables are coated with tin, and the tin diffuses into the copper at the temperatures prevailing in an incinerator, resulting in a reduction in the value of the copper.
A similar problem is encountered in processing tin cans (tin-plated iron). A major part of the tin diffuses into the iron under the incineration conditions. This requires expensive steps to render the iron suitable again for meticulous uses. However, these steps make it less attractive to recover iron from waste containing tin. A further problem that arises in processing waste materials is the environmental pollution caused by heavy metals often contained in the residues. These include, for instance, lead, antimony, and cadmium.
The object of the invention is to provide a process in which said waste products are processed in a simple and efficient way without attendant environmental problems, while also one or more valuable products can be recovered in a very pure form.